Trip mechanism for power shovels



Feb. 1o, 194s. .1.11. EDWARDS TRIP MECHANSM FOR 'OWER SHOVELS Filed March A28, 194e 2 Sheets-sheet 1 TRI? MECHANISM FOR POWER SHOVELS #Filed March 28, 194s 2 sheets-sheet 2 Jrn Egal/21:75

Patented Feb. 10,1948

James Hr-Edwards. lVillage of Welland-Junction,

Ontario, Canada Application March 28, 1946, Serial Notk'ljl ..3Glaims. (Cl.,214-].46)

The -invention -relatesetoeimprovements Y in trip mechanisms-for power-shovels which are Adevised -to -utilize a rotating member of the hoisting mechanisinfor trippingthebottom or door of Y the-bucket -or dipper.

'-Ihe major object ofthe invention is to provide -asemi-automatic tri-p of e the` kind referred to-whichis devised-to reduce to minimum the -eiort-required'by lthe operator in tripping `the Abueketefor release of the load.

Another object is to provide a trip mechanism -whiehefacilitatesand-expedities the operation of A.the 4excavating e machine. i conventional-trip cable of such .a machine demandsconsiderable effort on the part of the operator --in 4order to.unlatch the door of the clipper inthe-dumping operation. My invention is--oftheesemi-autornatic type and comprises a drawbarhaving a friction face and being slidably-mountedv -onv .a lcarriage .swingably suspended and manuallycperated by a counter-balanced vhand-lever. `:The `drawbar is attached to the trip cableanditsirictionface is brought into engagement .with the revolving hoist drum in ordertoepullethe `trip cable. :Means are pro- -vidednvzthe nature of' a take-up or compeneating device @for .keeping vthe trip cable vtaut inpositionalemovements of the .dipper handle.

4A .selected l.embodiment of the invention is shown in-theaaecompanying. drawing, in which:

fFig. y1l-is aside elevation partly in `section of -anpower shovel-embodying the improved trip mechanism.

@2 is .l ae-ifragmentary i axial section of the hoisting-drum vshowing -how the drawbarvengages anannularesurface thereof.

Fig. 3 is alongitudinal section pf the draw- K barand the supporting r`carriage.

4 is .a perspective ,view ofthe ,drawbar showing the friction face thereof.

Fig. 5 isatop planview of ,the carriage.

Fig. 6 isva cross section thereof -taken on line 6-6,,of1 ;Fig. 5.

Fiigniiis ,a perspective viewof'the ldipper `or hucketviewed `fromits bottom side to depict the ietchfmechanism, inherent.

Eier-.8 is a iront. elevation of the trip mechanism including the control lever but omitting the annular element of the hoisting drum by which the drawbar is actuated.

Fig. 9 is a cross section on line 9-9 of Fig. 1 depicting the pulley take-up device on the boom for the drawbar-cable.

The trip mechanism of this invention is associated with the regular hoisting drum, repre- 4tom or door material .such as to r.provide `a i the lower,` side `of the drawbar. Hing is rigidly applied as :by soft .metallrivets V,anmgllar frictionfacelfon `.the n .may be supplied by pa. ring orthe like vas atlg `integral with `orsecuredto the drum.

sented by the reference character lil. This drnm operates the hoisting cable Il for elevating and lowering thevdvipper'or Vbucket I2. -T he mechanism, such vas the gearing, .clutch andA brake, for operative control oimsaid` drum is not shownv in the drawing for the reason ythat it does not form a part of the invention.` -It will be understoojcl, however, by thosefamiliar with such ei;-

lcavating `machines that the drum is `connected by conventional mechanism to an Vengine in the swingbody or cab I3. The traction base of the swing body is indicated Lat I4, and the usual boom or beam is denoted at I5, on which ismounted the dipper hanzdlelS. The rack teeth I1 of rthe handle are engaged by ordinary gear mechanism (not shown) for crovvdingout and racking operations. This ,mechanism includes Aa shaft `I8 vjournalled on -the boom. ``"Ihisshait is nonly Vdriven duringracking in'and` racking out operations of the handle and its direction of rotation dependsonwhether the d ipper is being fedk outwardly or inwardly of the boom.

In .carrying outfthe, present invention, the shaft v-I8 is employed forthe operation of a takeup 0r compensating vdevice for .the trip ,cable .as

ywill be later described.

The invention comprises la rdravybar At9 ingthe form. 0f. anat-Sided elongated member Whith iS arranged above the ,hOiSt.i.I,1.g--d1U1n.wend 69.11.- nected to an endof a flexible. element@ which extends? from Athe latchv mechanism 9i 4the bob- 2| ofthebueket.Qrdieperll The flexible ,element is `a cablemor trip, rope which is pulledA to unlatch` said, bottom yor, door ltodis- .charge the contents 1of the bucket.

The .drawbar :is endwise slidable in .a

,riage or carrier22 at the undersidefthereof A,by

an arrangement :of roller bearirigamas at 2. Qn the `drawbar there l.is provided a y, cninna!rath/ely Short Strip Citrate-.Dirgete .Ore eemnereble rtien fece 0n The brake .1in-

The lining is4 disposed to'vbel engaged with an drum I0, which The carriage is swingable to and away from the drum, and has its inner end pivoted or hinged at 26 to a bar 26' or the like, which is fixedly supported in the cab I3. The free end of the carriage is supported by a control mechanism comprising a crank pivoted at 21 to a connecting bar 28 which in turn is pivoted at 29 to the carriage. The crank is composed of a shaft 30 horizontally journalled at 3l in the cab, and an arm 3l by which said crank is pivoted to the bar 28. On the crank is a counterweight 32 which balances the combined weight of the carriage and the drawbar. The carriage is manually controlled by a handlever 33 rigid with the crank and disposed conveniently to the operator within the cab.

In the operation of the machine, the drum l is rotated anti-clockwise to hoist the loaded bucket for dumping the load into a motor truck or the like. To open the door 2| of the bucket the operator pulls the lever 33 in order to lower the carriage so that the friction lining of the drawbar will make contact with the ring 25 of the revolving drum. The friction contact functions to forcibly retract the drawbar, thus pulling on the flexible element and releasing the latch of the bucket. In the pulling operation the fric-Y tion lining rides off the ring of the drum and automatically disengages the drawbar. VA stop piece 34 limits the inward travel of the drawbar and is engaged by a buffer 35 which desirably consists of -a block of rubber mounted on the inner end of the drawbar. The friction lining or pad is made of a length merely suilicient to cause the latch mechanism to have the necessary withdrawal movement and following this movement the operator pushes the lever 33 to raise the carriage to a normal position in which the friction lining will not cont-act the drum-ring on the return movement of the drawbar, which is selfreturning by reason of the pull exerted on the flexible element by the door of the bucket.

The latch mechanism preferably comprises a 31 to the bottom or doore2l of the bucket and arranged transversely of the spring-projected latch bar 38 to which it is pivoted at 39. The other lever, denoted at 40, is arranged transversely of the boom I6 and pivoted at an end at 4| thereto. The other end has a swivel connection 42 with a pulley 43 and is limited as to its swing by means of an element 44. The levers 36 and 40 are connected one to the other by a chain 45. the lever 40 outwardly of the bucket serves to withdraw the latch bar 38.

In order to keep the trip cable 20, normally taut irrespective of positional movement of the bucket, there is provided a, 4take-up or compensating device comprising the grooved pulleys 46 and 4l. The pulley 46 is loosely mounted on the shaft I8 aforesaid and the pulley 41 is fixedly mounted on this shaft for rotation therewith and is of a comparatively large diameter. The cable 20 is trained over the loose pulley 46 and the pulley 43. The outer cable end 48 is attached to the pulley 41 for winding and unwinding thereon. An idler pulley 49 on the boom is used to guide the inner end or stretch of this cable.

Since the pulley 4l is fixed on the shaft I8, it is turned according to the direction of endwise movement of the dipper handle I6 and in proportion to such movement with the result that 6 the trip cable is either wound on the kpulley 47 or unwound therefrom in order to take up any slack or to pay out the cable to maintain it taut.

By this arrangement, movement of.

,35 pair of levers of which the lever 36 is pivoted at It will be manifest that the invention provides a semi-automatic trip mechanism which not only requires but little manual effort to operate. but is also a time-saving appliance.

What I claim is:

1. In excavating mechanism of the class described, the combination with dipper door latch mechanism and a hoisting cable drum, of instrumentalities for operating the latch mechanism by utilizing the drum as a source of power comprising an annular friction face provided on the drum, a trip cable, a drawbar connected to the trip cable having a friction face for engaging that of the drum in order to pull the trip cable in an operational movement, a carriage supporting the drawbar for endwise movement and mounted for transversely shifting the drawbar to engagethe friction face thereof with that of the drum, a hand lever for operating the carriage, and a buffer on the drawbar for limiting the travel thereof in pulling the trip cable.

2. In excavating mechanism` of the class described, the combination with dipper door latch mechanism and a hoisting cable drum, of instrumentalities for operating the latch mechanism by utilizing the drum as a source of power comprising means providing an annular friction face rotatable with said drum,` a trip cable, a drawbar connected to the trip cable having a friction face for engaging said annular friction face, and means for reciprocably supporting the drawbar and for transversely shifting it for engagement of its friction face with said annular friction face, said means including a hand control, the structure being characterized in that the friction face of the drawbar is provided by a pad or strip of material such as brake lining of a length such that it will ride off said annular frictionLface when the necessary pull has been impartedto the trip cable, whereby to automatically sever the engagement of said friction faces.

3. In a power shovel, a dipper provided with a door, a latch mechanism for holding the door closed including a lever carrying a pulley, a dipper handle having rack teeth, gear means engaged with said rack teeth for crowding out and racking in operations, the gear means including a shaft, a pair of grooved pulleys mounted on the shaft, one of the pulleys being a loose pulley and the other a tight pulley, a trip cable having an inner end and an outer end, the cable being trained over said loose pulley and the pulley on said lever with its outer end connected to the vtight pulley, and a semi-automatic tripping device connected to the inner end of the cable.

JAMES H. EDWARDS.

REFERENCES CITED The following references are of record in the ille of this patent:l

UNITED STATES PATENTS E Date Culver May 2.6, 1931 

